This invention relates to a coupling portion for the manipulating wire of an endoscopic treatment instrument which is typically used to perform medical treatments in body cavities and which is adapted to be passed through a treatment instrument insertion channel in an endoscope.
Many of the endoscopic treatment instruments known in the art are designed such that distal end actuating members provided at the distal end are driven to operate by means of a manipulating wire that is remotely manipulated to move back and forth. Taking the case of endoscopic biopsy forceps, the manipulating wire is brought into engagement with engagement through-holes in the plate portions of the distal end actuating members by passing the distal end of the wire through the holes. While many versions of this technology have been known, Unexamined Published Japanese Patent Application (kokai) No. 178829/1999 proposes that the distal end of a manipulating wire be formed as a continuous loop and passed through engagement holes formed in the distal end actuating members. In the proposal made by European Patent No. 491890, a manipulating wire 81 passed through an engagement hole 83 is bent in two positions, one before and the other after the hole 83.
However, both proposals have their own disadvantages. In the first case, the distal end of the manipulating wire as passed through the engagement hole has to be formed in a continuous loop and this involves considerable difficulty in working and assembling operations, thus rendering the proposal a practically infeasible idea. In the second case, the manipulating wire 81 is simply bent both before and after the engagement hole 83; hence, if a strong external force is exerted on the distal end actuating members or if a strong pulling force is applied to the manipulating wire 81, the bent portions of the wire 81 stretch out and become straight enough that the wire 81 may slip out of the engagement hole 83.
Endoscopic treatment instruments such as endoscopic forceps mentioned above suffer from a further problem. The endoscopic forceps generally have a pair of forceps sections coupled integrally to associated drive levers (i.e. the distal end actuating members) and each combination of a forceps section and the associated drive lever is supported in the distal end portion of a sheath such that the forceps section and the drive lever are pivotal on a support shaft provided near the boundary. A manipulating wire is passed through the sheath and by manipulating it to move back and forth along the longitudinal axis, each forceps section and the associated drive lever pivot on the support shaft to drive the forceps sections such that they open and close like a bird""s beak.
In modern endoscopic forceps designed for simpler construction, the manipulating wire consists of two wires that are arranged side by side within the sheath and each of which is directly coupled at the distal end to the drive lever formed integral with an associated forceps section.
The problem with this design is that if two wires are simply arranged side by side, the pair of forceps sections are not synchronized in opening and closing motions and they just swing not to conform with the operator""s intention. To deal with this situation, the manipulating wire is entirely covered with a flexible heat-shrinking tube or the like in areas other than the distal end and its nearby portion, and the two wires are bundled to ensure that their distal end portions can move back and forth simultaneously.
However, covering the manipulating wire with a tube or the like results in increasing the thickness of the sheath by a corresponding amount and this has caused disadvantages such as applicability being limited to endoscopes having a thick enough forceps channel.
The present invention has been accomplished under these circumstances.
An object of the present invention is to provide an endoscopic treatment instrument of such a type that a manipulating wire is brought into engagement with engagement through-holes in the plate portions of distal end actuating members by passing the distal end of the wire through the holes and which can be worked and assembled in a sufficiently simple manner to feature high practical feasibility while exhibiting sufficient strength to prevent the manipulating wire from coming out of engagement with the engagement holes.
Another object of the present invention is to provide an endoscopic treatment instrument of such a type that two wires are directly coupled to respective drive levers to construct a manipulating wire and which allows a pair of forceps sections to open and close by equal degrees without increasing the diameter of the sheath.
Still another object of the present invention is to provide an endoscopic treatment instrument of such a type that the distal ends of wires are directly coupled to drive levers held pivotal in a slit and which can be operated satisfactorily for an adequate period without having the distal ends of the wires get stuck at the throat of the slit.
The present invention is characterized in that the distal end of the manipulating wire extending from the distal end of the sheath is provided with a large-diameter portion that is large enough to be incapable of passing through an engagement hole in the plate portion of the distal end actuating member.
The present invention is also characterized in that the manipulating wire as passed through the engagement hole until the large-diameter portion contacts an end portion of the engagement hole is bent back toward the distal end of the sheath at the other end of the engagement hole.
This design offers high practical feasibility since the structure that brings the manipulating wire into engagement with the distal end actuating member can be realized by simple working and assembling operations. In addition, the structure has a sufficient strength against the loss of engagement.
The present invention is also characterized in that an endoscopic forceps has two wires arranged side by side within a sheath to construct a manipulating wire, with the distal end of each wire being coupled to an associated drive lever (actuating member), and the two wires are twisted together within the sheath in the neighborhood or vicinity of its distal end.
Because of this design, the forceps sections formed integral with the drive levers can be opened and closed by equal degrees so that they accurately move as desired. In addition, this can be achieved without increasing the diameter of the sheath and, hence, the endoscopic forceps of the invention finds extensive use if it is passed through endoscopes that have built-in forceps channels of ordinary diameters.
The present invention is also characterized in that the surface of each of two drive levers (actuating members) which contacts the inner sidewall of a slit in the area closer to the rear end is skived in such a way as to create a gap or space with the inner sidewall of the slit and a wire extending from the tip of a sheath is pulled into the gap and coupled to the associated drive lever.
As a result, the end of each wire is located in a wide space whose width is one half the width of the slit and even if it deforms to spread somewhat, the wires will not get stuck at the throat of the slit and allow the forceps cups to be opened and closed in positive movements.
An endoscopic treatment instrument according to a preferred embodiment comprises:
a sheath having a longitudinal axis;
a manipulating wire passed through the sheath and movable back and forth along the longitudinal axis;
a distal end actuating member disposed at a distal end of the sheath and driven by the manipulating wire;
an engagement hole provided to a plate portion of the distal end actuating member; and
a large-diameter portion that is provided to a distal end of the manipulating wire and that is large enough to be incapable of passing through the engagement hole,
wherein the manipulating wire as passed through the engagement hole until the large-diameter portion contacts one end portion of the engagement hole is bent back toward the distal end of said sheath at the other end of the engagement hole.
The large-diameter portion may be formed by expanding the distal end of the manipulating wire and hardening the distal end thus expanded. In this case, the large-diameter portion may be formed by expanding the distal end of the manipulating wire, melting the thus expanded distal end and then hardening the thus molten distal end.
Alternatively, the large-diameter portion may be formed by fastening a spherical piece to the distal end of the manipulating wire, or by fastening a flange member to the distal end of the manipulating wire.
The manipulating wire may be twisted with another manipulating wire at least in the vicinity of the distal end of the distal end of the sheath.
The one end of the engagement hole is preferably located closer to the longitudinal axis of the sheath than the other end of the engagement hole is located. In this case, the other end of the engagement hole is preferably spaced from an inner sidewall of the slit provided in a support frame supporting the distal end actuating member.
An endoscopic treatment instrument according to another preferred embodiment comprises:
a sheath having a longitudinal axis;
a pair of manipulating wires passed through the sheath and movable back and forth along the longitudinal axis;
a pair of distal end actuating members disposed at a distal end of the sheath and connected respectively to the manipulating wires;
wherein the manipulating wires are twisted with each other within the sheath at least in the vicinity of the distal end of the sheath.
The manipulating wires may be twisted with each other only in the vicinity of the distal end of the sheath, or otherwise may be twisted with each other substantially entirely from the vicinity of the distal end of the sheath to a basal end of the sheath.
In the latter case, it is preferable that a pitch on which the manipulating wires are twisted is smaller in a foremost end portion of a twist area than in other areas.
The endoscopic treatment instrument may further comprise a support frame having a slit and movably supporting the distal end actuating members, and each of the distal end actuating members may have a skived portion at a rear end portion to define a space from an inner side wall of the slit, and a part of each manipulating wire, which extends from a corresponding distal end actuating member to the distal end of the sheath may be located within a corresponding space.
An endoscopic treatment instrument according to yet another preferred embodiment comprises:
a sheath-having a longitudinal axis;
a manipulating wire passed through the sheath and movable back and forth along the longitudinal axis;
a distal end actuating member disposed at a distal end of the sheath and driven by the manipulating wire;
a support frame movably supporting the distal end actuating member, and having a slit defining an inner sidewall; and
a skived portion provided to a rear end of the actuating member to define a space from the inner side wall, wherein the manipulating wire is passed through the space from the distal end of the sheath, and then connected to the actuating member.
The present disclosure relates to the subject matter contained in Japanese patent application Nos. Hei. 2000-61309 (filed on Mar. 7, 2000), 2000-142703 (filed on May 16, 2000) and 2000-162131 (filed on May 31, 2000), which are expressly incorporated herein by reference in their entireties.